An extract from the fruits of black pepper consisting of a minimum of 98% pure piperine was evaluated in a clinical study using a double-blind design. The relative bioavailability of 90 mg and 120 mg of coenzyme Q10 administered in a single-dose experiment or in separate experiments for 14 and 21 days with placebo or with 5 mg of piperine was determined by comparing measured changes in plasma c...

The structure of the mixed, enzyme-cofactor disulfide intermediate of ketopropyl-coenzyme M oxidoreductase/carboxylase has been determined by X-ray diffraction methods. Ketopropyl-coenzyme M oxidoreductase/carboxylase belongs to a family of pyridine nucleotide-containing flavin-dependent disulfide oxidoreductases, which couple the transfer of hydride derived from the NADPH to the reduction of p...

Coenzyme Q is well defined as a crucial component of the oxidative phosphorylation process in mitochondria which converts the energy in carbohydrates and fatty acids into ATP to drive cellular machinery and synthesis. New roles for coenzyme Q in other cellular functions are only becoming recognized. The new aspects have developed from the recognition that coenzyme Q can undergo oxidation/reduct...

When dl-1 ,2-propanediol-l-3H is converted to propionaldehyde in the presence of dioldehydrase and cobamide coenzyme, tritium is transferred to the coenzyme. The tritiated coenzyme so obtained transfers tritium to the reaction product when reacted with dl-1,2-propanediol and apoenzyme. The coenzyme is tritiated exclusively at the C-5’ position of the adenosyl moiety. The location of tritium was...

The NADPH-dependent dimeric flavoenzyme 4-hydroxyacetophenone monooxygenase (HAPMO) catalyzes Baeyer-Villiger oxidations of a wide range of ketones, thereby generating esters or lactones. In the current work, we probed HAPMO-coenzyme complexes present during the enzyme catalytic cycle with the aim to gain mechanistic insight. Moreover, we investigated the structural role of the nicotinamide coe...

Coenzyme Q10 is a fat soluble vitamin-like substance produced by the human body. It is necessary for proper functioning of many organs and for basic functioning of cells. It is found throughout the body. Coenzyme Q10 is used both as a food supplement and as an important antioxidant. It is a component of the electron transport chain and plays a key role in producing energy in mitochondria in the...

The structure of coenzyme Biz has been shown to be based upon that of vitamin Blz (1). The main structural differences between the coenzyme and the vitamin are the absence of cyanide and the presence of an adenine nucleoside in the coenzyme. An adenine nucleoside was isolated after photolysis of the coenzyme (2, 21). Although the photolysis reaction is complex and gives rise to two colorless ul...

Acetyl coenzyme A synthetase has been partially purified from many sources including yeast, bacteria, molds, plants, mammalian organs, and pigeon liver (5-11). Substrate amounts of this enzyme, partially purified by the method of Hele from beef heart mitochondria (lo), have been used for the isolation of acetyl adenylate from a reaction mixture containing all reactants except coenzyme A (4). Al...

The pathways involved in the biosynthesis of the benzoquinone ring of the ubiquinones have not been established. Recognition of the inability of mammals to synthesize aromatic rings de nova has led to the supposition that, in mammals, the benzoquinone ring of the ubiquinones arises from dietary aromatic amino acids. In support of this theory, Bentley et al. (1) administered phenylalanine-U-Cl4 ...

Woronick and Johnson (1) observed in Aspergillus niger extracts a pyruvate carboxylating system requiring adenosine triphosphate, but not involving phosphopyruvate, and suggested that the carboxylation reaction was coupled with the conversion of adenosine triphosphate to adenosine diphosphate and inorganic phosphate. Utter and Keech (2) studied a similar reaction in extracts of avian and beef l...